Engines, and particularly diesel engines, require fuel heaters during cold weather to prevent precipitation of wax from the fuel which tends to plug screens and fuel injectors. Heating of the fuel will correct this, but it is very easy to overheat the fuel, which gives it an abnormally low density which will have an effect on the fuel metering system.
The present invention overcomes these problems as the new heater includes a fuel temperature-actuated valve for bypassing the heated means in the heater.
For compactness, these fuel heaters are preferably elongated but of relatively small diameter with the temperature responsive operating means being located at one end of the heater, a valve body portion of the valve located at the opposite end and the two connected by an elongated stem. The valve body is slidably mounted in the tube in this type of construction with the tube having valve openings by means of which the control of the flow of the fuel is controlled.
Because of this elongated construction and the heating and cooling of the heater parts, it is sometimes possible for the lateral distortion of the valve stem to cause the valve body to tilt and bind with respect to the valve tube.